1. Field of the Invention
The present invention relates to a method for adjusting the switch-gap between the overlapping metal tongues of a reed switch contained in a glass envelope, in which a beam of radiation energy is directed through the envelope onto a localised area of at least one of the tongues for a specific period of time, thereby effecting permanent thermally-induced bending of the tongue in question about the irradiated area.
2. Description of the Related Art
Such a method is known from EP 0731978. Said document gives a very extensive description of the principle and the operation of a method for adjusting reed switches, wherein energy is irradiated onto a localised area of at least one of the tongues of the reed switch by means of a radiation source, for example a laser, resulting in a very large localised temperature increase, up to the melting point, effecting permanent bending of the tongue in question, so that the switch-gap formed with the other tongue is changed in a predetermined manner.
Since a great deal of background information on this type of method is provided in said document EP 0731978, said document is considered to be incorporated herein in its entirety.
Currently, an Argon-ion gas laser is used for adjusting reed switches upon production thereof, and to the best of the present inventor's knowledge this is the only laser available for mass production that supplies sufficient power in the frequency range from 488 to 522 nm.
This wavelength has been selected because the glass of the envelope exhibits a minimum absorption with said wavelength, so that damage to the glass caused by an excessive temperature is prevented. The Argon-ion gas laser that is used is a continuous laser which delivers a maximum power of 25 W. In order to be able to do so, the laser requires 55 kW of electric power. The waste heat of said laser must be removed via a thick cooling water pipe. Present in said laser is a plasma tube having a length of about 2 m and the weight of about 100 kg. Such a tube will last about 5500 hours, and it costs about Hfl. 100,000.-. The drawbacks of the use of such a laser operating in the aforesaid wavelength range are its large energy consumption, high cost and low flexibility and reliability.